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Title: Grain size effect on the giant dielectric constant of CaCu{sub 3}Ti{sub 4}O{sub 12} nanoceramics prepared by mechanosynthesis and spark plasma sintering

In the present work, CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) nanoceramics with different grain sizes were prepared by spark plasma sintering (SPS) at different temperatures (SPS-800, SPS-900, SPS-975, and SPS-1050) of the mechanosynthesized nano-powder. Structural and microstructural properties were studied by XRD and field-emission scanning electron microscope measurements. The grain size of CCTO nanoceramics increases from 80 nm to ∼200 nm for the ceramics sintered at 800 °C and 975 °C, respectively. Further increase of SPS temperature to 1050 °C leads to micro-sized ceramics of 2–3 μm. The electrical and dielectric properties of the investigated ceramics were studied by impedance spectroscopy. Giant dielectric constant was observed in CCTO nanoceramics. The dielectric constant increases with increasing the grain size of the nanoceramics with values of 8.3 × 10{sup 3}, 2.4 × 10{sup 4}, and 3.2 × 10{sup 4} for SPS-800, SPS-900, and SPS-975, respectively. For the micro-sized SPS-1050 ceramics, the dielectric constant dropped to 2.14 × 10{sup 4}. The dielectric behavior is interpreted within the internal barrier layer capacitance picture due to the electrical inhomogeneity of the ceramics. Besides the resistive grain boundaries that are usually observed in CCTO ceramics, domain boundaries appear as a second source of internal layers in the current nanoceramics.
Authors:
 [1] ;  [2] ;  [3]
  1. Department of Physics, College of Science, King Faisal University, Al-Ahsaa 31982 (Saudi Arabia)
  2. (Egypt)
  3. Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Narashino, Chiba 275-8575 (Japan)
Publication Date:
OSTI Identifier:
22273560
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 15; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 77 NANOSCIENCE AND NANOTECHNOLOGY; CAPACITANCE; CERAMICS; DEPLETION LAYER; FIELD EMISSION; GRAIN BOUNDARIES; GRAIN SIZE; IMPEDANCE; NANOSTRUCTURES; PERMITTIVITY; POWDERS; SCANNING ELECTRON MICROSCOPY; SINTERING; SPECTROSCOPY; TEMPERATURE DEPENDENCE; X-RAY DIFFRACTION